﻿var percent = prompt("Resize factor (percentage):","50");
var mySelection = app.project.selection;            
app.beginUndoGroup("scaleSelectedComps.jsx");      
for (var i = 0; i < mySelection.length; i++)
{
   if (mySelection[i] instanceof CompItem)
   {
      var compName = mySelection[i].name + " resized";
      compName = compName.substring(0,31);
      var W = Math.round(mySelection[i].width * percent/100);   
      var H = Math.round(mySelection[i].height* percent/100);
      var pixAsp = mySelection[i].pixelAspect;
      var Dur = mySelection[i].duration;
      var frRate = mySelection[i].frameRate;
      var resizedComp = app.project.items.addComp(compName,W,H,pixAsp,Dur,frRate);
      var myLayer = resizedComp.layers.add(mySelection[i]);
      myLayer.scale.setValue([percent,percent]);      
   }
}
app.endUndoGroup();